Red basal spots like those of the mimicking Pierines are in some cases found in the mimicked Heliconii: this is especially the case in those that form models for the Pierine genera Euterpe and Pereute. These spots are too widespread in the Pierine sub-family to have arisen from imitation of the Helicon; their presence in the latter is probably due to 'reciprocal mimicry' between distasteful forms, as suggested by the author in 'Trans. Ent. Soc. Lond.,' 1894, p. 298.

A curious case of a mimetic group is afforded by the Pierines Euterpe critias and E. bellona, together with their respective models Papilio zacynthus and the Heliconii of the thelaiope group. The Papilio and the Heliconi have no close resemblance to each other, but appear to be held together, as it were, by the intermediate Pierines. If the Heliconii are considered as the models for the whole group, the question arises why E. critins should copy a mimic, and not a very good one, instead of the original distasteful model. It is more probable that here also we have an instance of an 'inedible association;' this conclusion being strengthened by the fact that a certain amount of 'give and take,' or 'reciprocal mimicry,' seems to have occurred between the Pierines and the Papilio.

The paper was illustrated by coloured drawings of the species referred to.

6. On Certain Principles of Progressively Adaptive Variation Observed in Fossil Series. By Professor H. F. OSBORN.

7. On the Wing of Archaeopteryx
Modern Birds.
In this paper the author contended that certain of the Galliformes, such as the
common fowl and turkey for instance, are descended from an ancestral form of
a strictly arboreal habit, in which the pollex and index digits were armed with
claws to assist in climbing as well as to save itself from falling. These claws
remained functional until a sufficient number of the primary (and secondary)
remiges had developed to convert the wing into an organ of flight. Until this was
eflected, the development of these remiges nearest the wing (Nos. 8, 9, 10) was
arrested, so that the tip of the index digit might be left free for grasping. The
arrested development of the remiges referred to is the only clue we have left at
the present day, the claw of the second digit having been lost, whilst that and the
pollex are very small. These deductions were drawn from a precisely similar
arrangement shown by the author to exist in Opisthocomus cristatus, a bird which
shows many other unmistakably primitive characters.

Viewed in the Light of that of Some
By W. P. PYCRAFT.

It was also pointed out that there is reason for believing that the claws of Archæopteryx were of prime importance only during a similar period of life-the nestling period. A restoration in the shape of a model of the wing of Archeopteryx was exhibited, in which it was shown that the remiges rested upon the third digit, so as to leave the tip of the second free in a manner more or less resembling the nestling condition of Opisthocomus. It was, however, pointed out by the author that this digit might have supported the semiplume-like feathers seen in the fossil, overlying the quill feathers. These may have possibly extended to the tip of the second digit, and represented what we know as 'major' coverts.

8. On the Nephridial Duct of Owenia.
By Professor G. GILSON, of Louvain.

Owenia is a tubicolous annelid discovered by Delle Chiaje in the Gulf of Naples, and especially studied by Claparède. The latest writer on its anatomy, Dr. von Drasche, confesses his ignorance as to the presence or absence of the nephridia, as well as to the way through which the genital products are led out of the cœlom.

Although my own researches are far from terminated, I am able to give some information on the subject.

In fact, the nephridial system is not altogether absent, but is in a state of extreme reduction and seems to have lost all secretory function. It consists usually of one pair, sometimes two pairs, of very small funnels, lying in the posterior part of the sixth segment, against the muscular layer, in an extremely dorsal position.

Each of these funnels ends in a very thin tube, which passes through the muscular coat; but, instead of opening directly and freely on the epidermic surface, these tubes fall into a longitudinal duct which runs forward and opens, through a tiny pore, at the other end of the sixth segment.

This duct is a merely epithelial structure; it lies outside of the thick basal membrane, within the epiderm itself. Being thus superficially situated, it is exteriorly visible, and appears as a very sinuous line, extending the whole length of the sixth segment Dr. von Drasche, in his valuable monograph, very accurately represented this line, though he did not make out its significance.

I have seen this epithelial duct opening at certain places, thus taking the shape of a groove instead of that of a tube. These occasional imperfections of its structure, together with the peculiar disposition of its constituent cells, show that this canal originates as a longitudinal folding of the epithelium. They lead us also to consider it as an organ still in full course of phylogenetic evolution. Its utility, as well as the original cause of its formation, is obvious. I have shown elsewhere that the sandy tube in which the Owenia lives is rather tight round the fore end of the body. The genital products could scarcely reach the exterior were they directly ejected into the space between the worm and its protective sheath. The animal is obliged to protrude its body out of its dwelling, but, thanks to the epidermic canal, it is spared the trouble and danger of laying bare more than its five anterior segments, though the funnels lie in the posterior part of the sixth.

A question now presents itself: What is the morphological significance of this epidermic duct?

It is not my intention, in the present state of my researches, to enter into a full discussion of the subject. I shall content myself with calling attention to the bearing which the discovery of the epidermic canal of Owenia may have on the discussion of the homologies of the excretory system in general.

We know other instances of a longitudinal duct in connection with the nephridia. The most classical one is that of Lanice conchilega, described by Mr. Cunningham and Dr. E. Meyer.

The longitudinal duct of this species is generally regarded as an unsegmented part of the longitudinal row of cells which gives origin to the excretory system-an opinion which I have no reason to oppose.

But certain morphologists go further than that, and compare the longitudinal duct of Lanice, Polymmia, Polygordius, and others to the segmental canal or primitive ureter of vertebrates. Professor Wilson, in his remarkable paper on the germbands of Lumbricus, goes even so far as to consider this homology as evident.

On this point I venture to recall attention to Professor Haddon's hypothesis as to the phylogenetic origin and epiblastic nature of the segmental duct of vertebrates.

The existence of such an evidently adaptive structure as the epidermic duct of Owenia seems to give a remarkable confirmation to his suggestion as to how a continuous groove into which the nephridia opened may have been converted into a canal.

It is not evident at all that the segmental duct really is, in its whole length, an unsegmented part of a cell-row homologous to that of Clepsine or Lumbricus. It may have appeared at a much later period of the phylogenetic evolution, and have been, at a given moment, a new structure corresponding to new wants, just as the epidermic duct of Owenia corresponds to a peculiar disposition of the protective tube of the worm. The coexistence of a segmental duct analogous to the epithelial duct of Owenia, and of a structure homologous to the longitudinal canal of Lanice, is even possible.

I do not affirm that the epidermic duct of Owenia really represents the segmental duct at an early stage of its phylogenetic development. I rather think that we have here a case of homoplasy, not of homogeny. But I believe that the homology of the primitive ureter is not a settled question, as the American professor would have it, but that it remains a question open to further investigation.

DEPARTMENT OF BOTANY.

The following Papers were read:

1. On the Origin of the Sexual Organs of the Pteridophytes.
By Professor DOUGLAS H. CAMPBELL.

While the close affinity of the Bryophytes and Pteridophytes has been long recognised in the origin and early divisions of the sexual organs, there exist differences that have been looked upon as radical. This is especially noticeable in the archegonium.

A comparison of the structure and development of the sexual organs of the higher hepatics (Anthocerotia) with those of the Eusporangiate Pteridophytes, i.e., Ophioglosser, Marattiaces, Equisetinere, and Lycopodine, shows remarkable points of resemblance, enough to warrant the hypothesis that bere is to be sought the connection between the Bryophytes and Pteridophytes.

2. Notes upon the Germination of the Spores of the Ophioglosseæ.
By Professor DOUGLAS H. CAMPBELL.

The gametophytic stage of these plants is very imperfectly known, and hitherto only the very advanced conditions in two species.

The author succeeded in germinating two other species-Ophioglossum (Ophioderma) pendulum and Botrychium virginicum. In both the first division of the spore occurs before any chlorophyll is formed.

The author also found old prothallia of B. virginicum with young plants attached, but too far advanced to study the development of the reproductive organs and embryo.

3. On Sterilisation and a Theory of the Strobilus.
By Professor F. O. BOWER, F.R.S.

In submitting a theory of the strobilus to Section D it is assumed that Hofmeister's general conclusions will be accepted, that antithetic alternation was constant throughout the evolution of archegoniate plants, and that the sporophyte has been the result of elaboration of the zygote. The main points of the theory may be briefly stated as follows:

1. Spore-production was the first office of the sporophyte: its spore-bearing parts are to be regarded as primary, its vegetative parts as secondary in point of evolutionary history.

2. Other things being equal, increase in number of carpospores is an advantage. A climax of numerical spore-production was attained in homosporous vascular cryptogams.

3. Sterilisation of potential sporogenous tissue has been and is a widespread phenomenon, appearing as a natural consequence of increased spore-production.

4. Parts of the sterile tissue appeared as septa, partitioning off the remaining sporogenous tissue into separate loculi.

5. Septation to form synangia and subsequent separation of the sporangia are phenomena illustrated in the upward development of vascular plants.

6. Such septation may have taken place repeatedly in the same line of descent. 7. The sporogonial head as a whole is the correlative of the strobilus or flower, and the apex of the one corresponds to the apex of the other.

8. The progression from the one to the other depended upon (a) septation by formation of sterile partitions, (b) eruption of the surface to form appendicular organs upon which the sporangia are supported (sporangiophores, sporophylls).

9. The sporophylls, originally small and of simple form, were in the course of descent susceptible of great increase in size and complexity of form.

10. In certain cases foliage leaves were derived from sterilisation of sporophylls.

4. On a Method of Taking Casts of the Interiors of Flowers.
By Miss N. F. LAYARD.

5. On the Function of the Nucleus. By Professor E. ZACHARIAS.

6. Exhibition of Diagrams. By Professor LÉO ERrera.

TUESDAY, AUGUST 14.

DEPARTMENT OF ZOOLOGY.

The following Papers were read :

1. On the Blood of Magelona. By W. B. BENHAM, D.Sc.

The blood of this annelid differs entirely from that of any other chatopod hitherto examined. Instead of a red (hæmoglobinous) liquid plasma, in which float a few nucleated (colourless) corpuscles, or free nuclei, the blood-vessels of Magelona are completely filled with very small spherical globules of a madder-pink colour, floating in an extremely small amount of colourless plasma. These globules are not cells; there are free nuclei scattered amongst them, but the coloured globules are not nucleated. The colour of the globules is due to a pigment similar to hæmerythrin; the globules themselves, when shed, exhibit a marked tendency to run together like oil-drops and fuse with one another. This peculiar and rather viscous mass seems to be intermediate, in some respects, between the absolutely liquid, coloured plasma of chatopods generally and the red corpuscles of mammals, which float in a comparatively small amount of colourless plasma; further, the globules in Magelona probably originate, as those of mammals do, within cells, from which they are released.

2. Suggestions for a New Classification of the Polychata.
By W. B. BENHAM, D.Sc.

The Polychata may be divided into two grades-(a) the Eucephala, in which the prostomium retains its original condition as a lobe overhanging the mouth, and the peristomium shows no tendency to overgrow it. The body segments are all alike. The second grade (b) may be called Cryptocephala, as the peristomium grows forward and fuses with, or even entirely conceals, the prostomium, which is greatly reduced. The body segments are differentiated into two groups, indicated externally by the sudden alteration of the chatæ, and internally by certain differences.

The Eucephala includes four sub-orders :-

Sub-order 1. The Nereidiformia ( = Errantia, auct.) together with Aricüda.—In this group, with a few exceptions, the prostomium carries tentacles and palps, and

the peristomium usually carries special cirri. The parapodia are well-developed lobes, supported by strong acicula. The chætæ are jointed (gomphotrichs) or unjointed (holotrichs); no uncini occur. A pharynx exists, which frequently is armed with jaws. There are other characters drawn from internal organs.

Sub-order 2. Scoleciformia includes the four families-Ophelida, Arenicolidæ, Scalibregmida, and Maldanidæ.

The prostomium does not carry tentacles or palps, the peristomium is without special cirri. The parapodia are but feebly developed knobs or ridges, and are not supported by acicula. The chat are holotrichs. Sensory processes feebly developed or absent. Internally the most marked feature is the diminution in number of the nephridia connected with the incomplete character of the septa. There are no jaws, though the anterior end of the gut may be eversible.

Sub-order 3. Terebelliformia (Families.-Cirratulidæ, Chlorhamidæ, Sternaspidæ, Terebellidæ, &c.).—The prostomium carries tentacular appendages (the branchial processes of Chlorhamida). The achatous peristomium may carry filamentous processes. Parapodia, mere ridges or knobs; no acicula; chætæ are holotrichs and uncini. Dorsal cirri may be present on a few of the anterior segments, and they function as gills. Buccal region not eversible. Internally the nephridia present a dimorphism, accompanied in many cases by reduction in

number.

Sub-order 4. Capitelliformia includes the family Capitellida.

The second grade, Cryptocephala, is divided into two sub-orders :

Sub-order 1. Spioniformia (Families-Spionida, Magelonida, Chatopterida, Ammocharide) retains the prostomium as a small lobe, without definite tentacles or palps, but the peristomium is relatively large, and extends forwards on either side of the prostomium; this segment usually carries very long flexible tentacles. The parapodia are only feebly developed and incomplete; no acicula; the chata holotrichs; uncini may occur. Dorsal cirri, if present, become branchial organs. Buccal region eversible, but without jaws. Nephridia but imperfectly known.

Sub-order 2. Sabelliformia (Sabellida, Eriographida, Serpulida Hermellidæ). The prostomium is in most cases entirely concealed by the great development of the peristomium, and may be reduced to mere sensory knobs. But the palps are very greatly developed and function as gills. Parapodia only slightly projecting, mere ridges; chæta holotrichs and uncini. Dorsal cirri, if present, are branchial, or modified to form a thoracic membrane. Nephridia dimorphic-the anterior pair large, opening by a median dorsal pore on the first segment. remainder act as genital ducts.

or

3. On Museum Preparations. By E. S. GOODRICH.

4. On Random Publishing and Rules of Priority.
By THOMAS R. R. STEBBING, M.A.

The

Modern zoology is a study of continually extending scope. The literature is vast, costly, and polyglot. The channels of publication are so innumerable that naturalists can scarcely tell which way to turn. In books, in magazines, in reports of learned societies, the information required by one set of students is often so combined with that required by several other sets that the expense of obtaining it becomes prohibitory. The proposal is hazarded that the leading societies should set an example by arranging among themselves for a division of labour, in the hope that by degrees scientific workers might be induced to issue their new discoveries from a few well-recognised centres, instead of insisting on the present liberty of ubiquitous publication. A Committee of the British Association, it is suggested, might usefully undertake a preliminary consideration of what is possible or expedient in this respect; and, while ventilating the larger subject, might also propose a settlement of some debated questions of zoological nomenclature. A special proposal put forward is, that for every country there shall be a single authorised journal to receive the names of new genera and species, with